Guyselman Massif Loop Route

Guyselman Massif Loop Route

Page Type Page Type: Route
Location Lat/Lon: 39.75910°N / 106.27377°W
Additional Information Route Type: Mountaineering
Seasons Season: Spring, Summer
Additional Information Time Required: One to two days
Additional Information Difficulty: class 3 and 4
Sign the Climber's Log


First, I highly recommend using two days for this climb. A camp at Lost Lake makes a lot sense. Remember to bring mosquito repellent. Also, don’t waste your time with this adventure unless you have a stellar weather forecast. No need to caught in a T-storm along a two-mile ridge traverse in the middle of nowhere.

This ridge traverse was one of the highlights of the summer of 2005. I don’t ever recall being so far to each end of the spectrum when it came to enjoying a route. The hike to Lost Lake is very nice, and the camping is good too. However, the bushwhacking and the boulder hopping almost made me cry. Next, the 2 miles of ridge scrambling on pretty darn good rock with perfect views was a pure adrenaline rush. In retrospect, the bushwhacking and boulder fields were important experiences to the overall greatness of the climb, in sort of a masochist sort of way. There’s nothing like a good Gore bushwhack to get the blood flowing, for the mosquitos, of course!

Route Description

12 miles & 5,000-ft

From the parking area at 9,020-ft, hike southwest via the Brush Creek Trail 0.6 mile to a signed trail junction with the Gore Range Trail (39°47.854' N, 106°14.158' W.) Turn left, or south and follow the well-worn Gore Range Trail 1 mile and look sharp for the Lost Lake Trail on the right, it is signed (39°47.275' N, 106°13.861' W.) Ascend the Lost Lake Trail for 1.5 miles to a spot where the trail will cross Bush Creek (39°46.790' N, 106°15.244' W.) This section of trail is located in a flat, marshy area and it’s easy to lose due to the abundant plant life. Locate the creek first and then try to find a slight path through the wet, muddy area to cross the creek. Once across, locating the trail again is easy. Hike another .15 mile to Lost Lake at 10,143-ft. There is excellent camping where the trail finally meets the lake.

The lake rests below the boulder-ridden slopes of Peak O and it is almost completely encompassed by dense tree cover. It is a quite place, where you will most likely have the lake to yourself. From here, you cannot see Guyselman Mountain, but you can see the east ridge of Peak N and the east ridge of Guyselman. Locating the correct landmarks from Lost Lake is key; it won’t be long before you begin a tough bushwhack where landmarks are tough to locate. At this point, a GPS becomes very helpful.

After locating the east ridges of Guyselman and Peak N, locate the drainage that splits the two ridges. That’s where you want to go and be prepared for a boulder-hopping escapade that will slow your progress.

From Lost Lake, begin your happy, Gore style bushwhack by hiking south along the lakes east shoreline. Soon, leave the shoreline and bushwhack south 1.2 miles to a treed slope just under Peak O’s east ridge (39°46.004' N, 106°15.652' W.) From the words of a famous Colorado guidebook author “the introduction is over.” Traverse the boulder field between Peak O’s east ridge and Peak N’s east ridge for 0.3 mile to the base of Peak N’s east ridge (39°45.643' N, 106°15.682' W.) From here, make your way around Peak N’s impressive east ridge and begin a laborious climb up more car-sized boulders up into the basin under Guyselman’s great northeast face.

Guyselman’s northeast face will remind you that you are in the presence of sheer beauty: a massive wall of granite, which rarely gets viewed. I had thoughts of McHenry’s Peak from upper Spearhead Basin in Glacier Gorge.

Locate the weakness in Guyselman’s east ridge (39°45.159' N, 106°16.115' W,) a north-facing slope that requires easy class 2 hiking for about 400-ft to the crest. From here, the view of Peak N will make you weep. Once on the crest, ascend the ridge to the summit of Guyselman Mountain. From here, the view of Gore Thumb and Peak L will make you weep again. Guyselman’s summit view may be top 2 or 3 in the Gore Range.

The next objective is Peak N. Going forward, the route finding on the traverse may vary from my perspective, so be prepared for slight variations. From the summit, locate a steep, southwest-facing gully (39°45.095' N, 106°16.578' W.) Use this gully to skirt the huge drop-off from the summit to the east ridge. Descend it (class3 & 4) a 100+ft and cross over a rock rib to the north and make your way to a huge notch/col on the east ridge. From here, you will see a huge, soaring rock pinnacle and you can peer all the way down the northeast face of Guyselman. This is a cold and memorable place to be.

Locate a crux ramp that traverses the east side of the soaring rock pinnacle. Hike around the pinnacle and continue a class 3 ridge to the saddle between Guyselman and Peak N. Continue an ascent up Peak N’s south ridge to the summit (13,321-ft.)

The next objective is Peak O. First, overcome a daunting view of the ridge between the two peaks and begin a steep class 3 and 4 descent from the summit of Peak N. There are two enormous gendarmes that block the passage to Peak O. Locate and descend a series of class 3 and 4 crux ramps that will deposit you at the base of the first gendarme. Traverse the west side of the gendarme, staying as high as you can until you reach the second gendarme. Again, traverse the west side of the second gendarme via more class 3 and 4 scrambling. The sweeping south face of Peak O will be visible as you traverse the gendarme. Next, ascend the south ridge of Peak O to the summit and take a nap.

Begin your descent to Lost Lake by previewing your route choices. There are two possible routes. You can stay directly on the crest of Peak O’s north ridge and ride it down to Lost Lake. Be prepared for the longest boulder hopping experience of your life. Or you can descend the ridge crest to about 12,240-ft (39°46.133' N, 106°16.293' W) and continue a descent down the east slopes back to your original approach line (39°46.359' N, 106°15.564' W) through the trees. We chose this route mainly to get away from the continuous knee-busting slope down to Lost Lake. From Lost Lake, it’s hard to forget what that slope looks like and we didn’t want any part of it.

Descend your steep line of choice down into the trees and make your way back to Lost Lake. Continue 3.2 miles back to the Brush Creek TH.



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